1. Field of the Invention
The present invention relates to an image pickup apparatus having an optical path reflecting zoom lens system.
2. Description of the Related Art
In recent years, digital cameras (electronic cameras) have been gathering attention as next generation cameras replacing a silver-salt 35 mm film (135 format) camera. Furthermore, such digital cameras have a several categories in a wide range from a high-function type for professional use to a portable popular type.
A major bottleneck in making thin a depth of the camera has been a thickness of an optical system, particularly (a thickness) from a surface nearest to an object of a zoom lens system, up to an image surface. The mainstream of a camera body thinning technology nowadays has been using a so-called collapsible lens barrel in which, the optical system is protruded from a camera body at the time of taking and is accommodated in the camera body at the time of carrying. However, when the collapsible lens barrel is adopted, a time for a start-up from a lens-accommodated state to a usable state becomes long. Moreover, when a lens unit nearest to the object is let to be movable, it is disadvantageous for water proofing and dust proofing.
Lately, a digital camera in which there is no start-up time (time for protruding out of a lens) to the usable state of a camera as seen in the collapsible barrel, and which is favorable for water proofing and dust proofing, and moreover, which has a structure in which, an optical path (optical axis) of an optical system is allowed to be reflected by a reflecting optical member such as a mirror and a prism for making it a camera having an extremely thin depth, has come out.
Such an optical system is a system in which, a dimension in a direction of depth of the camera is made to be as thin as possible by adjusting an optical path upon reflection to a vertical or a horizontal direction of the camera body by providing a reflecting optical member in the optical system, as a lens unit in which a position of a lens unit nearest to the object is fixed with respect to an image pickup element.
Moreover, currently, in video cameras and digital cameras of a portable category, cameras having an image angle of 30° at a wide angle end have been main stream, and there is a need for further widening of an angle for widening a taking area.
As a zoom lens system in which an optical path reflecting optical system is adopted, having a wide angle, a zoom lens system has been disclosed in Japanese Patent Application Laid-open Publication No. 2004-354871, and Japanese Patent Application Laid-open Publication No. 2004-354869.